Frequently, a salient pole rotor machine is used to drive a load that is not balanced with respect to the rotor's axis of rotation, such as a compressor. Proper balancing of the load can improve a machine's performance, reduce a machine's operating noise, and extend a machine's operating life.
Conventional salient pole rotor machines, such as switched reluctance machines or synchronous reluctance machines, contain a rotor which rotates continuously. If the mass of the load being driven by the machine is unevenly distributed relative to the axis of rotation, then the system may wobble and vibrate as the rotor rotates. Besides producing noise, this excess motion causes the machine to operate less efficiently. In addition, these structural vibrations can cause fatigue in the machine's components and in any structure coupled to the rotor, and this wear-and-tear may result in premature deterioration or reduced life of the machine.
Current methods of balancing the load on these machines typically involve coupling a weight out board to the rotor shaft with a screw, pin, or other means, with the weight being positioned such that it counterbalances the off-balance load on the machine. The weight will typically abut the rotor, although it may be spaced apart from the rotor as well. By coupling an additional weight to the shaft, these processes can result in a system that is larger and therefore more problematic. Adding weight to the shaft can produce a machine that is larger, a compressor that is therefore taller, and a larger distance between bearings. Because a rotor in a salient pole rotor machine is subjected to significant normal forces during operation, these longer distances will cause the shaft to deform further during operation and thereby produce a noisier machine. In addition, wear on the machine components is increased. Thus, to date, efforts to resolve the problem of balancing a load in a salient pole rotor machine have proven inadequate.
This invention provides a simple, efficient means of balancing a load in a salient pole rotor machine without these complications.